Boron – Iron – Manganese

Abstract

The phase equilibria in the B-Fe-Mn ternary system have been investigated by several groups of authors [1952Hae, 1958Kot, 1966Kuz, 1975Pra2, 1976Pra]. The existence of the continuous solid solutions between Fe2B and Mn2B was reported by [1952Hae, 1958Kot] and that between FeB and MnB by [1952Hae]. This feature was confirmed by [1966Kuz], who presented an isothermal section at 800°C. [1966Kuz] prepared the samples from electrolytic Mn (99.5%), carbonyl Fe (99.99%), and B (99.5%). Carefully-mixed powders were pressed into briquettes and sintered at temperatures of 1300 to 1500°C for 3 h in an electric vacuum furnace. Some of the samples containing up to 20 at.% B were prepared by fusing in an electric resistance furnace using Al2O3 crucibles under a pure argon atmosphere. After annealing in quartz ampoules at 800°C for 300 to 500 h, the samples were quenched into cold water. Both the sintered and annealed samples were examined by X-ray diffraction (XRD) analysis. The experimental results suggested that the solubilities of Fe in Mn4B, Mn3B4, and MnB2 are negligible. Two partial isothermal sections at 850 and 1000°C with the B content up to 50 at.% were constructed by [1975Pra2]. Their experimental results indicated that in the temperature range of 850-1150°C two continuous solid solutions, (Mn1–xFex)2B and (Mn1–xFex)B, are in equilibrium. [1975Pra3] confirmed the tetragonal structure of (Mn1–xFex)2B and the rhombic structure of (Mn1–xFex)B and measured their lattice parameters as a function of composition. Using XRD, thermal analysis, and microstructure observation, [1976Pra] determined the liquidus projection below 60 at.% B and established two vertical sections at 33 at.% B and 50 at.% B. The experimental results due to [1976Pra] were reviewed by [1980Bra]. Effect of the Mn addition on the peritectoid reaction temperature of the Fe-0.2B (mass%) alloy was investigated by [1966Has] employing differential thermal analysis (DTA).